Serpentine spinal stability device

ABSTRACT

A spinal implant comprising a plurality of contiguous segments that define a segment array, said plurality of contiguous segments extending from a first side of the segment array to a second side of the segment array in an overlapping configuration, said plurality of contiguous segments operable to apply a torque to a degenerate spinal segment in each of three orthogonal axes. At least one mounting connection is configured to connect said spinal implant to a mounting mechanism, said mounting mechanism being configured to attach said spinal implant to said degenerate spinal segment.

PRIORITY CLAIM

This application claims the benefit of and priority from U.S.Provisional Patent Application Ser. No. 61/520,280, filed Jun. 7, 2011,and U.S. Provisional Patent Application Ser. No. 61/525,063, filed Aug.18, 2011; and is a Continuation-in-Part of U.S. patent application Ser.No. 12/709,240, filed Feb. 19, 2010, all of which are incorporatedherein in their entirety by this reference.

FIELD OF THE INVENTION

Embodiments of the present invention relate generally to mechanicalspinal implants and, more particularly, to dynamic spinal implants thatrelieve symptoms of degenerative spinal diseases, that restore healthymotion to an unhealthy spine, and that promote the healing of spinaltissues.

BACKGROUND

The human spine functions through a complex interaction of several partsof the anatomy. FIGS. 1 and 2 (the cross-section A-A of FIG. 1)illustrate a segment of the spine 4, with vertebra 5. The vertebra 5include the vertebral body 6, the spinous process 8, transverse process10, pedicle 12, and laminae 14. A functional spine, comprising severalvertebra 5, typically subcategorized as being part of the cervical,thoracic, lumbar, sacral, and coccygeal regions as known, providessupport to the head, neck, trunk, and transfer weight to lower limbs,protects the spinal cord 20, from which peripheral nerves 32 extend, andmaintain the body in an upright position while sitting or standing.

Also illustrated in FIGS. 1 and 2, the spinal segment 4 includesintervertebral discs 20 that separate adjacent vertebra 5. Theintervertebral discs 20 provide motion, load bearing and cushioningbetween adjacent vertebrae 5. Intervertebral discs 20 are the largestavascular structure in the body, relying on diffusion for its nutrition.The diffusion of nutrients is aided by the compression cycles that theintervertebral discs 20 undergo during the course of normal movement,which drives out waste products and cycles fluids. Lying down andresting reduces the load on the intervertebral discs 20 allowingnutrients to diffuse into the intervertebral discs 20.

Also illustrated in FIGS. 1 and 2, the spinal segment includes spinalfacet joints 16. Spinal facet joints 16 join the adjacent vertebrae 6.The spinal facet joints 16 are synovial joints that function much likethose of the fingers. Together with the intervertebral disc 20, thespinal facet joints 16 function to provide proper motion and stabilityto a spinal segment 4. Thus, each spinal segment 4 includes threejoints: the intervertebral disc 20 in the anterior aspect of the spinalsegment 4 and the two spinal facet joints 16 in the posterior aspect ofthe spinal segment 4.

For the spinal segment 4 to be healthy, each of the intervertebral disc20 and the spinal facet joints 16 must be healthy. To remain healthythese joints require motion. The intervertebral disc 20 and the spinalfacet joints 16 function together to provide both quality and quantityof motion. The quality of the motion is exhibited by the non-linearenergy storage (force-deflection, torque-rotation) behavior of thespinal segment 4. The quantity of motion is the range of segmentalrotation and translation.

Back pain due to diseased, damaged, and/or degraded intervertebral discs20 and/or spinal facet joints 16 is a significant health problem in theUnited States and globally. A non-exhaustive and non-limitingillustration of examples of diseased and/or damaged intervertebral discsare shown in FIG. 3. While a healthy intervertebral disc 20 isillustrated at the top of the spine segment 18, diseased and/or damageddiscs are also illustrated. The diseased and/or damaged discs include adegenerated disc 22, a bulging disc 24, a herniated disc 25, a thinningdisc 26, discs indicating symptoms of degeneration with osteophyteformation 28, as well as hypertrophic spinal facets 29.

A degenerating spinal segment 18 is believed to be the product ofadverse changes to its biochemistry and biomechanics. These adversechanges create a degenerative cascade affecting the quality and/orquantity of motion and may ultimately lead to pain. For example, as thehealth of a spinal segment 18 degenerates and/or changes, the spacethrough which the spinal cord 30 and peripheral nerves 32 (FIGS. 1 and2) pass can become constricted and thereby impinge a nerve, causingpain. For example, the spinal cord 30 or peripheral nerves 32 may becontacted by a bulging disc 24 or herniated disc 25 or hypertrophicspinal facet 29 as illustrated in FIG. 3. As another example, a changein the spinal segment 18, such as by a thinning disc 26 may alter theway in which the disc functions, such that the disc and spinal facetsmay not provide the stability or motion required to reduce muscle,ligament, and tendon strain. In other words, the muscular system isrequired to compensate for the structural deficiency and/or instabilityof the diseased spinal segment 18, resulting in muscle fatigue, tissuestrain, and hypertrophy of the spinal facets, further causing back pain.The pain this causes often leads patients to limit the pain-causingmotion; but this limited motion, while offering temporary relief, mayresult in longer-term harm. because the lack of motion limits theability of the disc to expel waste and obtain nutrients as discussedabove.

Of course, other diseases of the disc and other back related problemsand/or maladies afflict many people. For example, as the discdegenerates the spinal facet joints undergo a change in motion and inloading. This causes the spinal facet joints to begin to degenerate.Spinal facet joint arthritis is an additional source of pain. Also,scoliosis, or a lateral curvature of the spine, is illustrated in FIG.4. A patient's body 40 is illustrated in outline. Also illustrated isthe lateral curvature of a scoliotic spine 42 that is afflicted withscoliosis. The scoliotic center line 44 of the scoliotic spine 42 isillustrated, as compared to a healthy centerline or axis 46 of a healthyspinal column or functional spine unit. Conditions such as kyphosis, anexaggerated outward-posterior curvature of the thoracic region of thespine resulting in a rounded upper back, lordosis, an exaggeratedforward curvature of the lumbar and cervical regions of the spine, andother conditions also afflict some patients.

In many instances of degenerative disc disease, fusion of the vertebraeis the standard of care for surgical treatment, illustrated in FIG. 5.In the U.S. alone, approximately 349,000 spinal fusions are performedeach year at an estimated cost of $20.2 billion. The number of lowerback, or lumbar, fusions performed in the U.S. is expected to grow toapproximately 5 million annually by the year 2030 as the populationages, an increase of 2,200%.

Spinal fusion aims to limit the movement of the vertebra that areunstable or causing a patient pain and/or other symptoms. Spinal fusiontypically involves the removal of a diseased disc 50, illustrated inoutline in FIG. 5. The removed disc 50 is replaced by one or more fusioncages 52, which are filled or surrounded by autograft bone thattypically is harvested by excising one or more spinal facet joints 57.Vertebral bodies 51 adjacent the removed disc 50 are stabilized with oneor more posterior supports 58 that are fixedly connected to thevertebral bodies 51 with the use of pedicle screws 54 that arescrewed—such as by use of a bolt-style head 56 to turn the pedicle screw54—into a hole drilled into the pedicle 12 of the vertebral bodies 51.

Fusion, however, often fails to provide adequate or sufficient long-termrelief in about one-half of the treatments, resulting in low patientsatisfaction. Further, fusion, by definition, restricts the overallmotion of the treated functional spine unit, imposing increased stressesand range of motion on those portions of the spinal segment adjacent tothe fused vertebral bodies 51. Fusion of a spinal segment has beenindicated as a potential cause of degeneration to segments adjacent tothe fusion. The adjacent spinal facet joints 57 and adjacent discs 59often have to bear a greater load as a result of the fusion than wouldtypically be the case, leading to possible overloading and, in turn,degeneration. Thus, surgical fusion often provides short-term relief,but possibly greater long-term spinal degradation than would otherwisehave occurred.

Thus, a challenge to alleviating the back pain associated with variousailments is to find a remedy that, ideally, does not involve removingthe diseased disc or damaging the spinal facet joints, and that providessufficient stability to the diseased segment to alleviate pain and/orother symptoms, while still providing sufficient freedom of movement toallow the disc and spinal facet joints to return to health.

A further challenge is simply the complex, multi-dimensional nature ofmovement associated with a functional spine unit. Illustrated in FIG. 6are the varying, orthogonal axes around which a functional spine unitmoves. For example, a vertebra 5 is illustrated with an X-axis 60,around which a forward bending motion, or flexion, 61 in the anteriordirection occurs. Flexion 61 is the motion that occurs when a personbends forward, for example. A rearward bending motion, or extension, 62is also illustrated. The Y-axis 63 is the axis around which lateralextension, or bending, 64, left and right, occurs. The Z-axis 65 is theaxis around which axial rotation 66, left and right, occurs. Spinalfusion, as discussed above, limits or prevents flexion 61-extension 62,but also limits or prevents motion in lateral extension, or bending, 64and axial rotation 66. Thus, an improved alternative remedy to fusionpreferably allows for movement with improved stability around each ofthe three axes, 60, 63, and 65.

Another difficulty associated with the complex motion of the spine isthat the center-of-rotation for movement around each of the X-axis 60,Y-axis 63, and Z-axis 65 differs for each axis. This is illustrated inFIG. 7, in which the center-of-rotation for the flexion 61-extension 62motion around the X-axis 60 is located at flexion-extensioncenter-of-rotation 70. The center-of-rotation for the lateral extension,or bending, 64 motion around the Y-axis 63 is located at lateralextension, or bending, center-of-rotation 73. The center-of-rotation forthe axial rotation 66 around the Z-axis 65 is located at axial rotationcenter-of-rotation 75. For more complex motion patterns (e.g., combinedflexion, lateral extension/bending, etc.) a two-dimensionalrepresentation of the center-of-rotation is inadequate, but thethree-dimensional equivalent called the helical axis of motion, orinstantaneous screw axis can be employed. Spinal remedies which forcerotation of a spinal segment around any axis other than the naturalhelical axis impose additional stresses on the tissue structures at boththe diseased spinal segments and the adjacent spinal segments.Compounding the issue for the centers-of-rotation is that they actuallychange location during the movement, i.e., the location of thecenters-of-rotation are instantaneous. Thus, a preferable remedy tospinal problems would account for the different instantaneouscenters-of-rotation throughout the range of motion. Stated differently,a preferable remedy to spinal problems would allow the diseased spinalsegment and adjacent spinal segments to under motion approximate that ofthe natural helical axis through the range of motions.

Many previous efforts have been made to solve at least some of theproblems associated with spinal fusion, but with varying degrees ofsuccess. For example, U.S. Pat. No. 7,632,292 (the '292 patent) toSengupta and Mulholland, discloses an arched-shaped spring mechanismthat is attached to adjacent vertebrae via pedicle screws. This devicerelies on the extension and compression of the spring to accommodateflexion 61 and extension 62 about the X-axis 60 illustrated in FIG. 6.The device disclosed in the '292 patent addresses only flexion-extensionand neither lateral extension/bending nor axial rotation, which wouldboth still be improperly supported. Further, the '292 patent does notaccount for the instantaneous centers-of-rotation; in other words, thecenters-of-rotation will be misplaced for motions other than flexion. Inaddition, it may be anticipated that the device is either too stiff toprovide proper motion or that the extension-compression cycles may leadto fatigue failure of the device.

Another example is U.S. Pat. No. 6,966,910 (the '910 patent) and itsassociated family of applications to Ritland. As with the '292 patent,the '910 patent relies on the extension-compression cycle of a springmechanism—specifically the reverse curves within the mechanism—toaccommodate flexion 61 and extension 62 about the X-axis 60 illustratedin FIG. 6. Lateral extension/bending and axial rotation are notaddressed.

SUMMARY

In accordance with one aspect of the invention, a spinal implant isprovided, including a plurality of contiguous segments that define asegment array, said plurality of contiguous segments extending from afirst side of the segment array to a second side of the segment array inan overlapping configuration. The plurality of contiguous segments canbe operable to apply a torque to a degenerate spinal segment in each ofthree orthogonal axes. At least one mounting connection can beconfigured to connect the spinal implant to a mounting mechanism, saidmounting mechanism being configured to attach the spinal implant to thedegenerate spinal segment.

In accordance with another aspect of the invention, a spinal implant isprovided, including a plurality of contiguous segments that define asegment array. The plurality of contiguous segments can extend from afirst side of the segment array to a second side of the segment array inan overlapping configuration. The plurality of contiguous segments caninclude substantially flat portions that include rectangular crosssections that are connected through a series of curved end portions thatconnect each substantially flat portion to an adjacent flat portion. Atleast one mounting connection can be configured to connect said spinalimplant to a mounting mechanism, the mounting mechanism being configuredto attach said spinal implant to said degenerate spinal segment.

In accordance with another aspect of the invention, a method of treatinga spinal segment is provided, comprising: obtaining at least one spinalimplant configured to apply a torque to at least one vertebra adjacentto an intervertebral disc, said spinal implant including: a plurality ofcontiguous segments that define a segment array, said plurality ofcontiguous segments extending from a first side of the segment array toa second side of the segment array in an overlapping configuration, saidplurality of contiguous segments operable to apply a torque to a spinalsegment in each of three orthogonal axes; and at least one mountingconnection configured to connect said spinal implant to a mountingmechanism, said mounting mechanism being configured to attach saidspinal implant to said spinal segment; and, implanting said spinalimplant to said vertebra such that said torque distracts said vertebrafrom said intervertebral disc.

Additional advantages of the present invention will become readilyapparent from the following discussion, particularly when taken togetherwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of theone or more present inventions, reference to specific embodimentsthereof are illustrated in the appended drawings. The drawings depictonly exemplary embodiments and are therefore not to be consideredlimiting. One or more embodiments will be described and explained withadditional specificity and detail through the use of the accompanyingdrawings in which:

FIG. 1 is a segment of a functional spine unit;

FIG. 2 is a cross-section of the segment of the functional spine unitillustrated in FIG. 1, taken along section A-A of FIG. 1;

FIG. 3 is a segment of a spine illustrating various pathologies ofintervertebral discs;

FIG. 4 is a scoliotic spine;

FIG. 5 is a prior art discectomy and spinal fusion;

FIG. 6 illustrates the three axes of motion around which functionalspine unit moves;

FIG. 7 illustrates the centers-of-motion of a functional spine unit;

FIG. 8 illustrates an embodiment of an unimplanted compliant dynamicspinal implant, shown from the rear/posterior view, i.e., as it wouldappear from the rear of a person when implanted;

FIG. 9 is a lateral/side view of the spinal implant shown in FIG. 8;

FIG. 10 shows embodiments of the spinal implant as they would appearimplanted in a pair of lumbar vertebrae as viewed from the rear;

FIG. 11 is a lateral view of the spinal implant of FIG. 10 undergoing acompressive load and a torsional load;

FIG. 12 is a graph of the rotation that occurs for a given torque for anexemplary healthy spine and an exemplary degenerative spine undergoingflexion and extension;

FIG. 13 is a graph of the moment difference between the response of thedegenerative spine and the healthy spine graphed in FIG. 12 and a linearcurve fit of the moment difference;

FIG. 14 is a graph of the healthy spine of FIG. 12 and the resultantrotation that occurs for a given torque of the degenerative spine (shownin FIG. 12) that has had an embodiment of the spinal implant that hasbeen adjusted to exhibit a torque response that is the negative slope ofthe linear curve fit shown in FIG. 13; and

FIG. 15 is a schematic view of a generalized implant configuration inaccordance with an embodiment of the invention.

The drawings are not necessarily to scale.

DETAILED DESCRIPTION

Before the present invention is disclosed and described, it is to beunderstood that this invention is not limited to the particularstructures, process steps, or materials disclosed herein, but isextended to equivalents thereof as would be recognized by those ofordinarily skilled in the relevant arts. It should also be understoodthat terminology employed herein is used for the purpose of describingparticular embodiments only and is not intended to be limiting.

It must be noted that, as used in this specification and the appendedclaims, the singular forms “a” and “the” can include plural referents,unless the context clearly dictates otherwise. Thus, for example,reference to a “container” can include reference to one or more of suchcontainers.

DEFINITIONS

In describing and claiming the present invention, the followingterminology will be used.

As used herein, the term “ribbon” is to be understood to refer to acomponent (or a material forming a component) that has a thickness thatis much smaller than its width. In one example, the thickness of theribbon is at least four times smaller than is its width.

As used herein, relative terms, such as “upper,” “lower,” “upwardly,”“downwardly,” “vertically,” etc., are used to refer to variouscomponents, and orientations of components, of the systems discussedherein, and related structures with which the present systems can beutilized, as those terms would be readily understood by one of ordinaryskill in the relevant art. It is to be understood that such terms arenot intended to limit the present invention but are used to aid indescribing the components of the present systems, and related structuresgenerally, in the most straightforward manner.

As used herein, the term “substantially” refers to the complete ornearly complete extent or degree of an action, characteristic, property,state, structure, item, or result. As an arbitrary example, when anobject or group of objects is/are referred to as being “substantially”symmetrical, it is to be understood that the object or objects areeither completely symmetrical or are nearly completely symmetrical. Theexact allowable degree of deviation from absolute completeness may insome cases depend on the specific context. However, generally speakingthe nearness of completion will be so as to have the same overall resultas if absolute and total completion were obtained.

The use of “substantially” is equally applicable when used in a negativeconnotation to refer to the complete or near complete lack of an action,characteristic, property, state, structure, item, or result. As anarbitrary example, an opening that is “substantially free of” materialwould either completely lack material, or so nearly completely lackmaterial that the effect would be the same as if it completely lackedmaterial. In other words, an opening that is “substantially free of”material may still actually contain some such material as long as thereis no measurable effect as a result thereof.

As used herein, the term “about” is used to provide flexibility to anumerical range endpoint by providing that a given value may be “alittle above” or “a little below” the endpoint.

Distances, forces, weights, amounts, and other numerical data may beexpressed or presented herein in a range format. It is to be understoodthat such a range format is used merely for convenience and brevity andthus should be interpreted flexibly to include not only the numericalvalues explicitly recited as the limits of the range, but also toinclude all the individual numerical values or sub-ranges encompassedwithin that range as if each numerical value and sub-range is explicitlyrecited.

As an illustration, a numerical range of “about 1 inch to about 5inches” should be interpreted to include not only the explicitly recitedvalues of about 1 inch to about 5 inches, but also include individualvalues and sub-ranges within the indicated range. Thus, included in thisnumerical range are individual values such as 2, 3, and 4 and sub-rangessuch as from 1-3, from 2-4, and from 3-5, etc.

This same principle applies to ranges reciting only one numerical valueand should apply regardless of the breadth of the range or thecharacteristics being described.

INVENTION

As noted above, the kinetics and kinematics of the spine are quitecomplex, involving three separate axes around which motion occurs andthree separate centers-of-rotation for the different motions. Applicantshave recognized that previous spinal implants often address just oneform of motion, typically flexion and extension, often through the useof springs of some type that flex and compress. Efforts to address morethan one mode of rotation or motion typically tend to be complex, large,and often do not address each individual motion as effectively asdevices dedicated to a single motion.

Through significant experimentation and engineering work, Applicantshave discovered geometries that rely, in part, on the concept oftorsion, rather than primarily compression and extension of springs, toprovide a seemingly simple, yet decidedly complex, geometry thataccommodates motion and stiffness around the three axis and accommodatesthe separate centers-of-rotation for each motion (flexion-extension,lateral extension or bending, and axial rotation). A compliant mechanismgains its motion from the deflection of flexible, resilient members.Such devices move without the aid of traditional sliding joints andbearings, thus increasing precision and eliminating friction and wear.They also integrate spring and hinge functions, allowing for the designof desired force-deflection behavior.

An embodiment of a compliant dynamic spinal implant 100 is illustratedin FIGS. 8 and 9, which is an embodiment of a geometry thataccomplishes, in part, the objectives provided above. A posterior viewof the spinal implant 100 is presented in FIG. 8—reference being made tothe direction the spinal implant would be viewed from when implanted ina patient. In other words, the spinal implant 100 in FIG. 8 appears asit would as viewed it from the patient's back. A lateral, or side, view,of the implant is presented in FIG. 9. It will be understood that whilethese references to view are presented for clarity, it should beunderstood the spinal implants 100 shown in FIGS. 8 and 9 appear intheir unstressed, pre-implant condition, as will be explained in furtherdetail below.

In this particular embodiment, the spinal implant 100 comprises aplurality of contiguous segments. In one embodiment, these contiguoussegments define a segment array that includes segments (which include,but are not limited to, 102, 104, 106, etc.) that extend from a firstside of the segment array to a second side of the segment array in anoverlapping configuration. The segments are operable to apply a torqueto a degenerate spinal segment in each of three orthogonal axes. Theimplant can include at least one mounting connection 130 configured toconnect said spinal implant to a mounting mechanism. Such mountingmechanism (one shown by example at 202 in FIG. 11 as a pedicle screw)can be configured to attach the spinal implant to a degenerate spinalsegment. While not so required, in one aspect of the invention, thesegment array is substantially centered between two mounting mechanisms.

The array of segments 102, 104, 106, etc., are arranged in a generallyserpentine orientation and provide many of the advantages ofconventional spinal implants in much more compact package size. Forexample, in one embodiment of the invention, the overall volume consumedby the array is as small as 12×12×15 mm while providing a 100 N reactionforce at 2 mm of deflection. Such package size is much smaller than canbe achieved by functional spinal implants found in the prior art.

The segments 102, 104, 106, etc., are generally each joined by acontinuously curving end segment (e.g., 103 in FIG. 9) that transitionsfrom one segment (102) to an adjacent, overlapping segment (104). Thecontinuous, serpentine material aids in providing smooth force responseto loads applied to the implant, while minimizing the size requirementof the implant. In one aspect of the invention, a continuous ribbon ofmaterial alternately and contiguously extends from one side of the arrayto another side of the array in an overlapping configuration. The sizeand shape of the various segments of the array are discussed in furtherdetail below, in conjunction with FIG. 15.

In accordance with one aspect of the invention, an insert (120 in FIGS.8 and 9) can be positioned between two of the segments of the segmentarray. The insert can be operable to alter a force-deflectioncharacteristic of the spinal implant. In the example shown (probablybest appreciated in FIG. 9), the insert includes a generally curvilinearsurface along which segment 104 is forced to track as the implant iscompressed. One of ordinary skill in the art, having possession of thisdisclosure, will readily appreciate that constraining the bending ofsegment 104 along the surface of the insert 120 will alter theforce-deflection response of the segment, and thereby theforce-deflection response of the implant. While the insert shown willperform primarily as the implant compresses, inserts can also beinserted that alter the force-deflection characteristics of the spinalimplant as it expands (e.g., as a tensile force is applied to theimplant).

The shape and size of the insert 120 can be varied to achieve a desiredforce-deflection response from the implant 100 that can be tailored totreat a specific patient for a specific condition. The discussionrelating to FIGS. 12, 13 and 14 addresses this aspect of the inventionin greater detail.

As shown in FIGS. 8 through 10, in one embodiment, a protective shroud140 can be provided. The shroud 140 can be fittable about the spinalimplant 100 and can aid in limiting or preventing surrounding tissuefrom contacting the spinal implant. The shroud can be formed from avariety of materials, including biocompatible polymers and the like. Asbest seen in FIG. 8, the shroud can generally fit about the mountingconnections 130 and can be formed in two parts that can befriction-pressed together after installation of the implant 100.Alternately, the shroud can be formed about the implant prior toinstallation.

The shroud 140 can also provide a manner by which the insert 120 can bemaintained in position within the segments 102, 104, etc. of the implant100. By coupling the insert to the shroud, the insert need notnecessarily be attached to any portion of the implant, but will still bemaintained in proper position relative to the implant.

The spinal implant 100 optionally includes at least one mountingconnection (130 in FIGS. 8 and 9, for example) for connecting the spinalimplant 100 to a mounting mechanism. For example, an embodiment of amounting connection includes through holes, through which a mountingmechanism, typically, although not necessarily, a pedicle screw, ispositioned to hold the spinal implant in position in the patient—i.e.,the mounting mechanism attaches the spinal implant 100 to at least aportion of a spinal segment, such as a vertebra, a pedicle, or otherbony structure of a patient as will be discussed below. Of course,pedicle screws are merely one example of a mounting mechanism forattaching the spinal implant 100 to a patient's vertebrae. Othermounting mechanisms, such as the use of pins, biocompatible adhesives,straps, and the like, fall within the scope of this disclosure.

The spinal implant 100 can be formed of biocompatible plastics,polymers, metals, metal alloys, laminates, shape-memory materials, andother similar materials, either wholly as one material or as acombination of materials—i.e., different segments may be manufacturedfrom different materials. Optionally, embodiments of the spinal implantcan be made from bioabsorbable materials that a patient's body willnaturally breakdown over time, thus potentially avoiding the need for asecond surgery to remove the spinal implant 100, should such an optionprove necessary and/or desirable.

An embodiment of the spinal implant 100 can optionally be made withnitinol, a metal alloy of nickel and titanium, that provides the abilityof shape-memory. A spinal implant 100 made from such materials would bemanufactured into a first shape or geometry or configuration having aknown and desired first torque response. The spinal implant 100 wouldthen be manipulated into a second shape or geometry having a known anddesired second torque response. The spinal implant 100, in the secondshape or geometry or configuration, then would be implanted in thepatient. After implantation, a physician can apply an activating agent,such as heat, current, or other parameter, to cause the spinal implant100 to revert back to its original, first shape or geometry, allowingthe material to consequently revert to its first torque response. Thus,a measure of adjustability in the torque response of the spinal implant100—even post-surgery—can be manufactured into the spinal implant 100.For example, in the case of nitinol, applying a parameter such as heatto the spinal implant and, in so doing, raising the spinal implant to atemperature above the transition temperature of the nitinol causes thespinal implant to revert to its first shape or geometry. In so doing,the stiffness of the spinal implant could be altered by, for example,making the spinal implant significantly stiffer so that it approximatesmore closely the stiffness provided by a spinal fusion procedure.

Another embodiment of the spinal implant 100 can be made frombioabsorbable materials, as mentioned. The patient's body would slowlyabsorb the spinal implant 100 and, in the process of so doing, thecompressive load or force and torque provided or born by the spinalimplant 100 would slowly be transferred to the intervertebral discsand/or vertebrae of the patient as the patient's spine healed and/orimproved in health and strength. Thus, a bioabsorbable devicecontemplates and allows for a patient to regain his or her spinalhealth, an adjustment and transfer of force and torque from the spinalimplant to the patient's body, and the eventual removal of the spinalimplant through absorption rather than surgery.

While the various segments are typically shown as a continuous, orcontiguous, unit, the various segments 102, 104, 106, etc., can bejoined to one another. When the term “joined” is used herein, it isunderstood that the segments may be temporarily joined, through aremovable connection, such as bolts, screws, biocompatible adhesives,and the like. Alternatively, one or more of the segments may be joinedpermanently, such as through the use of biocompatible epoxies, polymers,and other known methods of joining the segments. In yet anotherembodiment, the individual segments may be formed as a single, unitarypiece, such as by laminating, molding, pressing, stamping, milling, andother known methods.

An advantage of embodiments of the spinal implants disclosed—providedthat they are manufactured as single, unitary piece—is that they do nothave any joints or surfaces that might rub or wear against each otherbecause the embodiments rely on deflection of the segment(s) to providea force and/or torque. The relative lack of rubbing or movement againstother elements as compared to prior art devices minimizes or preventsthe formation of wear particles that might otherwise be generated. Thisis the case for those prior art devices that have biocompatible surfacesthat might wear off to expose non-biocompatible surfaces or, in someinstances, the wear causes the biocompatible surface to becomenon-biocompatible, leading to additional wearing of the prior artdevices at an accelerated rate.

For context, FIG. 10 generally, and FIG. 11 specifically, illustrateembodiments of the spinal implants 100 as they might appear implanted ona lumbar portion of the spine of a patient. As shown in FIG. 11, thespinal implants 100 are fixed to the vertebrae 204 adjacent to adiseased disc 206. In this embodiment, pedicle screws 202 are used tofix the spinal implants 200 to the vertebrae 204. (The method ofsurgical implantation will be discussed in more detail below.) Onceimplanted, the spinal implants 100 optionally provide an extensionforce, if they are prestressed, as will be discussed below, to helpdistract the vertebrae 204 from the diseased disc 206. Alternatively,the spinal implants 100 resist a compressive force 214 from the normalaction of gravity upon the person, thus supporting a portion of the loadthat would otherwise have been born by the diseased disc 206. Inaddition, the spinal implants provide a torque 212 (about an axisperpendicular to the page of FIG. 11) that distracts the diseased disc206 and, preferably, distracts an anterior portion 207 of the diseaseddisc 206. The torque 212 applied by the spinal implants 100 can beselected and adjusted to compensate at least partially and, preferably,almost fully, for the diseased disc 206, as will be explained furtherbelow.

A benefit of embodiments of the spinal implant is that they can beindividually adjusted to a specific patient and that patient'spathologies, rather than relying on prior art devices that weremanufactured for a predetermined subset of the population. Thedisadvantages of the latter approach are that it is rare that anindividual patient's pathologies, by coincidence, are an exact match fora device. Thus, the patient must compromise, to a greater or lesserextent, on the performance and the relief that may be obtained throughthe use of some prior art devices. The implants can be tailored toprovide a preferred, or “target” or “treatment” response to a particularpatient's spinal condition. For example, the torque applied in any ofthe three axes of rotation can match that of a healthy spine (if that isthe target treatment for the particular patient), or can overcompensate(e.g., apply a greater torque than a healthy spine would experience)when attempting to correct for some misalignment in the spine.

Referring to FIGS. 12-14, an exemplary process for selecting andadjusting a spinal implant to a patient's pathology will be discussed.FIG. 12 is a graph of the torque-rotation response of a healthy and adiseased or degenerative disc undergoing flexion and extension, i.e.,rotation in flexion 61 and extension 62 around the X-axis 60 asillustrated in FIG. 6 and corresponding to bending or leaning over andbending or leaning backwards. The X-axis 300 of the graph is the torquemeasured in Newton·meters (Nm). The Y-axis 305 of the graph is ameasurement of the range of motion in rotation in degrees. The solid(healthy) curve 310 is the response of a healthy functional spine unitwhich, for example, can include the disc 208 illustrated in FIG. 11.

The dotted (degenerate) curve 315 is the response of a diseased ordegenerative disc, such as disc 206 illustrated in FIG. 11.Qualitatively, FIG. 12 indicates that the diseased disc rotates more atlower torque than the healthy disc, indicating that there is a greaterdegree of laxity in the diseased disc, which may present as the discbulging anteriorly and pressing against the spinal cord, causing pain,and/or other similar pathology. These measurements can be taken for thespine, as a whole, but, more preferably, the measurements are made atthe vertebrae adjacent to the diseased disc. This is so because thetorque-rotation response of the adjacent healthy vertebrae and discsshould be the most similar to the response of the diseased disc when itwas once healthy, a consideration since it is desired to restore thediseased disc to health.

Referring now to FIG. 13, this graph uses the same axes and scale as thegraph in FIG. 12. In this instance, FIG. 13 plots the solid (momentdifference) curve 320, which is the calculated difference in theresponse between the solid (healthy) curve 310 and the dotted(degenerate) curve 315 in FIG. 12. The dashed (linear) curve 325 is alinear curve fit of the solid (moment difference) curve 320.

A difference and improvement in the embodiments of the spinal implantdisclosed herein is that the geometry of the spinal implant optionallyuses this calculated moment difference as an input in the designprocess. The spinal implant 100 can, for example, be designed to providea desired and known torque response when implanted in the patient asdiscussed above. In this example, the spinal implant 100 would have alinear torque-rotation response in flexion-extension that has a slopethat is the negative of the dashed (linear) curve 325.

FIG. 14 illustrates the reason for creating a spinal implant thatrelies, in part, on the moment difference between the healthy disc andthe diseased disc. Again, the same axes and scale are used in FIG. 14 asin FIG. 12. In this graph, the original solid (healthy) curve 310 isplotted. Now, however, a spinal implant designed and adjusted for thepatient's pathology, has been implanted as described above. In otherwords, a spinal implant 100 is now supporting the diseased disc 206 andthe adjacent vertebrae 204. As can be seen in FIG. 14, the spinalimplant provides a desired stiffness, restoring the response of thedotted (degenerate) curve 315 to that of the dashed (linear anddegenerate) curve 330 that is similar to the solid (healthy) curve 210.Qualitatively, it can be seen that with the spinal implant, therotational response for a given torque is quite near that of the healthydisc.

While this example is provided for flexion and extension, one havingskill in the art would understand that similar measurements can be madefor lateral extension and axial rotation so that the results can beused, in part, as an input into the geometry of the spinal implant and,therefore, to allow the spinal implant to accommodate and support themotion of the spine in the three axes as discussed above. In brief,embodiments of the spinal implant can be designed and adjusted, in part,pre-operatively for an individual patient's pathology. Embodiments ofthe spinal implant can restore, at least in part, a healthytorque-rotation signature to a diseased spine.

A further advantage of the above approach of measuring torque-rotationand similar data for use as an input is that it avoids a problem thatappears in prior art devices. As briefly alluded to, many prior artdevices have a limited range over which they function, typicallyforce-displacement in compression and extension for the devices thatcommonly rely upon springs. These devices are not typically calibratedto an individual. As a result, it is not uncommon for these prior artdevices to distract the diseased disc using an extension force that istoo large for a given individual, causing undue strain on thesurrounding muscles and ligaments, which may result in undue pain. Insevere cases, the pain this causes might result in the patient undulylimiting his or her range of motion, resulting in nutritionaldeficiencies and other problems associated with minimal or a lack ofmovement in the spine and the disc, which was the outcome to be avoidedinitially.

FIG. 15 illustrates exemplary geometries of the implant 100 with thedesign variables defined (tl, tl2, tl3, bl, bl2, bl3 and sh). Note that,due to the symmetry of the device, the variables apply to both the topand bottom half of the device. An additional dimension, the width of thebeams, is measured in the y direction of FIG. 15 (and shown at “W” inFIG. 8). The device was displacement loaded for an exemplary loadinganalysis.

Table I below illustrates exemplary design responses for differingobjectives:

TABLE I Objective 1 2 3a 3b Width 4.88 mm 12 mm 15 mm 18 m sh 0.55 mm0.91 mm 1.29 mm 1.45 mm tl 3.87 mm 6.00 mm 7.5 mm 9.0 mm tl2 3.24 mm6.00 mm 7.5 mm 9.0 mm tl3 6.00 mm 6.00 mm 7.5 mm 9.0 mm bl 2.09 mm 1.58mm 1.95 mm 2.12 mm bl2 1.22 mm 1.58 mm 1.95 mm 2.12 mm bl3 4.19 mm 4.40mm 3.59 mm 3.46 mm del 0 mm −0.1 mm 0.0 mm −0.37 mm force    0N 4.45N4.35N 38.6N stress 0 Pa 21.0 MPa 10.0 MPa 68.8 MPa force2 13.96N 93.4N191.5N  246.2.N   stress2 422 MPa 440 MPa 440 MPa 440 MPa

In this exemplary design optimization test, three objectives weretargeted. Objective 1 had a target force (force2) of 14N and minimizedthe geometric variables tl, tl2, tl3, bl, bl2, bl3, sh and width.Objective 2 maximized force for the previously mentioned geometricconstraints. Objective 3 had two parts: 3a had a target pre-load force(force1) of 100N and maximized force at the final deflection (force2),while maintaining the geometric constrains of 15 mm in x, 15 mm in y,and 15 mm in z. Objective 3b used the same pre-load force objectives asObjective 3a and maximized the final deflection force (force2) whilemaintaining the geometric constraints of 18 mm in x, 18 mm in y, and 15mm in z.

The data show that the geometry of the implant can be much smaller thanconventional units by utilizing the serpentine configuration, whilestill providing the same axial force-deflection profile. It was alsoshown that the serpentine design can attain very stiff force deflectioncharacteristics, while fitting in the design restraints of 12 mm in xand y and being able to deflect the necessary 2 mm (again, compared tothe limitations of a conventional device). If the geometric constraintsare relaxed by 3 mm and 6 mm in the x and y direction while maintainingthe geometric constraint in the z direction, a much stiffer device ispossible, attaining up to 191.5N at final deflection or 38.6N of forceat preload and 246.2N of force at final deflection.

Embodiments of the spinal implant disclosed herein provide additionalbenefits, such as:

Treating Scoliosis, Kyphosis, Lordosis, and/or Similar Pathologies:

For example, with reference to FIG. 4 which illustrates a spinepresenting with scoliosis, embodiments of the disclosed spinal implantcan treat the scoliosis. This is done by using spinal implants that havedifferent torque-rotation signatures from each other. That is, ratherthan using spinal implants 100 having the same torque-rotation signatureas illustrated in FIG. 10, in the instance of scoliosis one of thespinal implants would have a different and, possibly, opposite,torque-rotation signature than the other. In addition, a prestressedforce may be applied to one or both of the spinal implants so that theyapply a force to one or both sides of the scoliotic spine. In otherwords, the torque and/or any force applied by the spinal implants wouldbe unbalanced in order to counteract the curvature of the scolioticspine. For example, in FIG. 4 an extensive force 82 can be applied onthe right side of the lumbar area of the spine by one spinal implant,while on the left side another spinal implant could apply a compressiveforce on the left side of the lumbar area of the spine, tending to causethe lumbar spine to straighten. Alternatively, or in addition to, theunbalanced forces, torques 84 and 86 could be applied to the spine bythe spinal implants. A similar strategy could be used to treat otherconditions of the spine that present similar pathology to scoliosis,such as kyphosis, lordosis, and the like.

Provide Distraction of the Vertebrae to Allow Healing of the DiseasedDisc:

As noted, a spinal implant can be prestressed to provide a torque and/orextensive force to distract, either anteriorly, posteriorly, or both,the portion the vertebrae adjacent to a diseased disc. In so doing, thespinal implants carry or bear a portion of the force normally borne bythe diseased disc, as well as an additional force that static devicessuch as the prior art posterior support 58 in FIG. 5 do not carry. Thisarrangement allows sufficient support and space for the diseased disc toheal while still providing for sufficient moment that static prior artdevices and procedures (such as spinal fusion) do not provide. In otherwords, embodiments of the spinal implant provide an opportunity for thediseased disc to heal, which may allow the spinal implants to eventuallybe removed.

Protect Spinal Cord and Periphery Nerves:

The embodiments disclosed provide, in part, a measure of protection tothe spinal cord and peripheral nerves from being impinged by bulgingand/or herniated discs and/or parts of the skeletal structure and otherparts of the anatomy afflicted with various pathologies as describedabove.

Limit Range of Motion and Provide Stiffness:

The embodiments disclosed, as shown graphically in FIGS. 12-14, restorea measure of stiffness and limit the range of motion that mightotherwise be causing pain, such as through muscles overexertingthemselves to compensate for the laxity caused by a diseased disc. Bylimiting the range of motion, the strain on muscles and ligaments isreduced, thereby reducing risk of injury to those muscles. Further,laxity is reduced, thereby improving the structural stiffness (asopposed to the colloquial muscle stiffness caused by over-exertion) ofthe spine.

Kinetics Similar to a Healthy Spine:

Related to limiting the range of motion discussed above, the motion thatembodiments of the spinal implant provide in the three axes discussedabove regarding FIG. 6 is similar to that of a healthy spine. What thisprovides is that the patient's muscles and ligaments do not have tocompensate for an unnatural motion of the spinal implant, unlike thecase with prior art devices. In other words, the spinal implant providesmore natural motion, which would encourage patients to move more withless attendant pain as their muscles would not be compensating oroverworking for a prior art spinal implant that does not provide suchnatural motion around all three axes. In so doing, the movement providesfurther nutrition to the discs, increasing the likelihood that the discswill heal.

Kinematics Similar to a Healthy Spine:

Related to the kinetics are the natural kinematics of embodiments of thespinal implants. As discussed above, the centers-of-rotation forflexion-extension, lateral extension/bending, and axial rotation, areeach located in different places. Prior art devices could notaccommodate these separate centers-of-rotation around more than oneaxis, if even that, nor could they provide for the instantaneous or nearinstantaneous change in the location of the centers-of-motion as aspinal segment moves, nor could they provide for motion approximate themotion of a natural helical axis. Stated differently, thecenter-of-rotation of prior art devices often was in a differentlocation than the natural center-of-rotation of the spine for a givenmovement. To compensate, patients with prior art devices suffered strainupon the spinal cord and peripheral nerves, muscle strain caused by themuscles overworking and compensating for the two differentcenters-of-rotation (that of the prior art device and that of thespine), ligament strain, and, consequently, pain. In contrast,embodiments of the present spinal implant provide centers-of-rotation ineach of the three axes that is the same, or nearly the same, as apatient's natural centers-of-rotation for the spine. Thus, patientstypically have less pain and, consequently, greater movement, to thebenefit of the discs and the spine in general.

Adjust to the Individual Spine:

As noted, embodiments of the spinal implant can be designed and/orselected preoperatively for an individual patient's torque-rotationresponse in order to provide implants that restore the diseaseddisc/spine to near healthy function. Related to this is the ability toprestress embodiments of the implant prior to, or even during, surgeryto allow the surgeon to further individually tailor the torque-rotationresponse of the spinal implant to the individual patient as determinedat the time.

Further, embodiments of the spinal implant are adjustablepost-surgically. As noted, spinal implants made of bioabsorbablematerial will gradually degrade and, in the process, transfer evergreater portions of the force and torque once borne by the spinalimplant back to the patient's spine as it heals. A further benefit ofthis is that these embodiments do not need to then be surgicallyremoved, reducing cost and risks to the patient. Alternatively,embodiments of the spinal implant can be made from shape-memorymaterials, such as nitinol. The use of shape memory materials allows thespinal implant to be configured in a second geometry or shape uponsurgical implantation and then, upon application of some transformationparameter, such as heat, the spinal implant reverts to a first geometryor shape with different mechanical properties (such as stiffness and/ortorque), thus allowing a physician to subsequently alter the treatmentof the patient without surgical intervention.

Reduced Wear:

As noted, embodiments of the spinal implant do not have movingcomponents or components that rub against one another, thereby reducingor eliminating the generation of wear particles. Further, becauseembodiments of the spinal implant rely upon torsion and/or torsion beamsrather than compression and extension that springs and other similardevices rely upon, reduces or eliminates the risk of the material fromwhich the spinal implant is made suffers from fatigue and/or fatiguefailure, thereby increasing the reliability of the spinal implant.

Thus, disclosed above, in addition to the embodiments of the spinalimplant are methods of treating a spine with a spinal implant configuredto provide motion in three axes; methods of treating a spine with aspinal implant that provides kinetics and kinematics similar to that ofa functional spine; methods of treating pathologies that cause the spineto curve; methods of healing a diseased or degenerated disc; methods ofadjusting a spinal implant without surgical intervention; methods ofreducing the wear of a spinal implant; methods of providing a nearhealthy torque-rotation signature to a degenerate spine; and othermethods as will be recognized by one of skill in the art.

As alluded to above, embodiments of the spinal implant are surgicallyimplanted. While the spinal implants disclosed herein can be implantedusing either an anterior, posterior, or lateral incision in the patient,a preferred method is to use a posterior incision. Further, it ispreferred that a minimally invasive procedure be used, such as bylaparoscopy in which only one or a few, small incisions are made and thesurgery is conducted with laparoscopic tools. The methods include makingan incision; providing an embodiment of the spinal implant disclosedherein; using a positioning tool to position the spinal implant andcounter and prestress designed into the spinal implant; and fixing thespinal implant to two adjacent vertebrae. The surgical procedure doesnot require that the disc space be distracted extensively to install thespinal implant, thereby reducing the pain and recovery time endured bythe patient. The method optionally includes implanting spinal implantswith different characteristics, such as different prestressed torques,for treating pathologies such as scoliosis. Fixing the spinal implant tothe vertebrae may be done by applying straps, applying biocompatibleadhesives, installing pedicle screws, and the like, as known in the art.

Alternative methods and positions of placing the spinal implant includelocating them on the anterior side of the spine rather than theposterior side. Spinal implants positioned to the anterior side can bereached through an incision in the patient's back and positioned betweenthe transverse process of adjacent vertebral bodies or mechanicallyattached to the anterior portion of the vertebral body.

The present invention, in various embodiments, includes providingdevices and processes in the absence of items not depicted and/ordescribed herein or in various embodiments hereof, including in theabsence of such items as may have been used in previous devices orprocesses, e.g., for improving performance, achieving ease and/orreducing cost of implementation.

The foregoing discussion of the invention has been presented forpurposes of illustration and description. The foregoing is not intendedto limit the invention to the form or forms disclosed herein. In theforegoing Detailed Description for example, various features of theinvention are grouped together in one or more embodiments for thepurpose of streamlining the disclosure. This method of disclosure is notto be interpreted as reflecting an intention that the claimed inventionrequires more features than are expressly recited in each claim. Rather,as the following claims reflect, inventive aspects lie in less than allfeatures of a single foregoing disclosed embodiment. Thus, the followingclaims are hereby incorporated into this Detailed Description, with eachclaim standing on its own as a separate preferred embodiment of theinvention.

Moreover, though the description of the invention has includeddescription of one or more embodiments and certain variations andmodifications, other variations and modifications are within the scopeof the invention, e.g., as may be within the skill and knowledge ofthose in the art, after understanding the present disclosure. It isintended to obtain rights which include alternative embodiments to theextent permitted, including alternate, interchangeable and/or equivalentstructures, functions, ranges or steps to those claimed, whether or notsuch alternate, interchangeable and/or equivalent structures, functions,ranges or steps are disclosed herein, and without intending to publiclydedicate any patentable subject matter.

What is claimed is:
 1. A spinal implant comprising: a plurality ofcontiguous segments that define a segment array, said plurality ofcontiguous segments extending from a first side of the segment array toa second side of the segment array in an overlapping configuration, saidplurality of contiguous segments operable to apply a torque to adegenerate spinal segment in each of three orthogonal axes; and at leastone mounting connection configured to connect said spinal implant to amounting mechanism, said mounting mechanism being configured to attachsaid spinal implant to said degenerate spinal segment.
 2. The spinalimplant of claim 1, wherein each of said plurality of contiguoussegments are joined by a continuously curving end segment thattransitions from one segment to an adjacent, overlapping segment.
 3. Thespinal implant of claim 1, wherein the array of contiguous segments isformed from a ribbon of material that alternately and contiguouslyextends from one side of the array to another side of the array in anoverlapping configuration.
 4. The spinal implant of claim 1, wherein thearray includes at least four overlapping segments.
 5. The spinal implantof claim 1, wherein the array of contiguous segments is substantiallycentered between the two mounting connections.
 6. The spinal implant ofclaim 1, further comprising at least one insert positioned between twoof the segments of the segment array, the insert operable to alter aforce-deflection characteristic of the spinal implant.
 7. The spinalimplant of claim 6, wherein the at least one insert includes a roundedprofile along which one or more of the two segments is bent duringdeflection of the spinal implant.
 8. The spinal implant of claim 1,further comprising a protective shroud, fittable about the spinalimplant, the protective shroud configured to limit surrounding tissuefrom contacting the spinal implant.
 9. The spinal implant of claim 8,further comprising at least one insert positioned between two of thesegments of the segment array, the insert operable to alter aforce-deflection characteristic of the spinal implant.
 10. The spinalimplant of claim 9, wherein the protective shroud is coupleable to theinsert.
 11. A spinal implant comprising: a plurality of contiguoussegments that define a segment array, said plurality of contiguoussegments extending from a first side of the segment array to a secondside of the segment array in an overlapping configuration, saidplurality of contiguous segments including substantially flat portionsincluding rectangular cross sections that are connected through a seriesof curved end portions that connect each substantially flat portion toan adjacent flat portion; at least one mounting connection configured toconnect said spinal implant to a mounting mechanism, said mountingmechanism being configured to attach said spinal implant to saiddegenerate spinal segment.
 12. The spinal implant of claim 11, whereinthe rectangular cross section of each of said plurality of contiguoussegments includes a width at least four times a thickness of thesubstantially flat portions.
 13. The spinal implant of claim 11, whereinthe plurality of contiguous segments are operable to apply a torque to adegenerate spinal segment in each of three orthogonal axes.
 14. Thespinal implant of claim 11, further comprising two mounting connections,disposed on opposing ends of the array of contiguous segments.
 15. Thespinal implant of claim 14, wherein the array of contiguous segments issubstantially centered between the two mounting connections.
 16. Thespinal implant of claim 11, further comprising at least one insertpositioned between two of the contiguous segments, the insert altering aforce-deflection characteristic of the implant.
 17. The spinal implantof claim 16, wherein the at least one insert includes a rounded profilealong which one or more of the segments are bent during deflection ofthe spinal implant.
 18. The spinal implant of claim 11, furthercomprising a protective shroud, fittable about the spinal implant, theprotective shroud configured to limit surrounding tissue from contactingthe spinal implant.
 19. The spinal implant of claim 18, furthercomprising at least one insert positioned between two of the segments ofthe segment array, the insert operable to alter a force-deflectioncharacteristic of the spinal implant, the protective shroud beingcoupleable to the insert.
 20. A method of treating a spinal segmentcomprising: obtaining at least one spinal implant configured to apply atorque to at least one vertebra adjacent to an intervertebral disc, saidspinal implant including: a plurality of contiguous segments that definea segment array, said plurality of contiguous segments extending from afirst side of the segment array to a second side of the segment array inan overlapping configuration, said plurality of contiguous segmentsoperable to apply a torque to a spinal segment in each of threeorthogonal axes; and at least one mounting connection configured toconnect said spinal implant to a mounting mechanism, said mountingmechanism being configured to attach said spinal implant to said spinalsegment; and, implanting said spinal implant to said vertebra such thatsaid torque distracts said vertebra from said intervertebral disc.